warning for one cycle will do very little good. it generally takes longer than that for any distros to start using a kernel and get it into the hands of the users (and in the embedded space where ARM is so strong, it's even worse)
but even if it only took a week for a distro to QA and ship a kernel, and users started putting pressure on immediately, there is no chance for any development work to take place and still make it into the mainline kernel before the merge window closes.
it will probably take multiple kernel cycles before the warning is seen by any users who don't compile their own kernels, and then more time for the pressure from the users to build up, and then development time to fix the problem, and then time to merge the fixes upstream.
I don't see this taking place in less than a year, and probably a lot longer before everything is fixed.